Thanks Smartys. I need a little more help since I am not exactly familiar with PHP.
I copied and pasted this code somewhere in the middle of the register.php page:
{
// Load the "welcome" template
$mail_tpl = trim(file_get_contents(PUN_ROOT.'lang/'.$pun_user['language'].'/mail_templates/welcome.tpl'));
// The first row contains the subject
$first_crlf = strpos($mail_tpl, "\n");
$mail_subject = trim(substr($mail_tpl, 8, $first_crlf-8));
$mail_message = trim(substr($mail_tpl, $first_crlf));
$mail_subject = str_replace('<board_title>', $pun_config['o_board_title'], $mail_subject);
$mail_message = str_replace('<base_url>', $pun_config['o_base_url'].'/', $mail_message);
$mail_message = str_replace('<username>', $username, $mail_message);
$mail_message = str_replace('<password>', $password1, $mail_message);
$mail_message = str_replace('<login_url>', $pun_config['o_base_url'].'/login.php', $mail_message);
$mail_message = str_replace('<board_mailer>', $pun_config['o_board_title'].' '.$lang_common['Mailer'], $mail_message);
pun_mail($email1, $mail_subject, $mail_message);
message($lang_register['Reg e-mail'].' <a href="mailto:'.$pun_config['o_admin_email'].'">'.$pun_config['o_admin_email'].'</a>.', true);
}
I checked it and the mail is being sent perfectly. 
However, I would like to modify the content of the mail a little. For example, I would like to remove the word "Mailer" from the 'From', remove the line asking them to login to activate and instead have a welcome sentence. Where do I edit the variables in?
Regards.
